The present invention is directed to a wet oxidation procedure for treatment of waste streams to remove organic impurities and substantially limit corrosion of the materials utilized in the practice of the procedure. In particular, the present invention is directed to a wet oxidation procedure for the treatment of acrylonitrile waste streams to remove organic impurities.
Wet oxidation is a well established process for treating aqueous waste waters, sludges and slurries which contain oxidizable substances. Many patents and publications disclose wet oxidation processes using air as a source of oxygen for accomplishing the oxidation. In addition, other patents disclose the application of pure oxygen or an oxygen enriched gas in a wet oxidation procedure. See for example U.S. Pat. Nos. 4,384,959; 3,042,489; 3,097,988; 3,654,070; 3,359,200; 3,272,740; 4,395,339 and 4,744,909.
Increased reaction rates and the opportunity to operate at lower pressures and temperatures has made the use of oxygen enriched gas/pure oxygen very attractive from a theoretical standpoint. In addition, many potential users of wet oxidation processes, such as sewage treatment plants, steel mills, etc., have existing oxygen generation/storage facilities making the gas available at low cost. However, in spite of these facts wet oxidation processes using enriched/pure oxygen are difficult to operate because of safety considerations and associated corrosion problems.
Pure oxygen or oxygen enriched gas can be used to enhance the rate and completeness of oxidation. However, the presence of oxygen at higher concentrations, especially high purity oxygen is likely to raise concerns regarding spontaneous combustion when placed in contact with organic or other oxidizable substances at pressures above atmospheric, indeed, even at room temperature. Therefore, it is absolutely vital to control the wet oxidation process parameters when using oxygen enriched systems to minimize the hazardous operating conditions and corrosion problems associated therewith. The present invention is directed to a safe, economical means of oxidizing organic impurities present in waste streams in particular, waste streams generated in the production of acrylonitrile by the use of enriched oxygen which does not require sophisticated materials of construction (i.e., expensive) or elaborate equipment designs.